An active regenerative solar still is analysed in this paper on the basis of energy balances for its different components. Analytical expressions are derived for water and glass temperatures, daily yield and thermal efficiency as a function of climatic as well as design parameters. The optimum condition for higher yield from the proposed system has also been discussed analytically. The following conclusions are drawn for a particular set of parameters.
1. (i) Passive regenerative solar stills have better thermal efficiency than active regenerative solar stills, and
2. (ii) Thermal efficiency increases with increase in the flow of water velocity.